www.defra.gov.uk Eel Management plans for the United Kingdom Anglian River Basin District Date published: March 2010 Contents 1. Introduction 2. Description of the Anglian River Basin District 2.1 The Anglian River Basin District 2.2 Current eel population 2.3 The Fishery 2.4 Silver eel escapement 2.5 Eel mortality and available habitat 3. Restocking 3.1 Need for restocking 3.2 Past restocking 3.3 Stocking study in the Anglian RBD 3.4 Compliance with restocking requirements in the Regulation. 4. Monitoring 4.1 Assessment of silver eel escapement 4.2 Price Monitoring and reporting system 4.3 Catch and effort sampling system 4.4 Traceability of live imported and exported eels 5. Measures 5.1 Measures to meet Escapement Objective 5.2 Measures taken 2007 to 2009 5.3 Measures to be taken 2009 to 2012 5.4 Measures to be taken beyond 2012 to achieve Escapement Objective 6. Control and Enforcement 7. Modification of Eel Management Plans Appendices • Appendix A1 • Appendix A2 • Appendix A3 • Appendix A4 • Appendix A5 • Appendix A6 Eel management plans for Anglian River Basin District Page 2 1. Introduction This Eel Management Plan for the Anglian River Basin District (RBD) aims to describe the current status of eel populations, assess compliance with the target set out in Council Regulation No 1100/2007 and detail management measures to increase silver eel escapement. This will contribute to the recovery of the stock of European eel. 2 Description of the Anglian River Basin District 2.1 The Anglian River Basin District The Anglian RBD comprises several large catchments in the northern and south western parts of the RBD, e.g. the Nene, Welland, Witham, Great Ouse and Ely Ouse, as well as multiple smaller catchments throughout, including the Yare, Bure, Waveney, Gipping, Blackwater, Chelmer, Stour and Colne, which are in the south eastern part of the RBD. The rivers all drain to the North Sea along the east coast of England, between the Thames estuary to the south, and the Humber estuary to the north. The numbers and areas of four main water body types, as defined by the Water Framework Directive, are shown in Table 2.1 (Defra, 2005). Water body type Number present Length/Area Rivers with catchments greater 6,426 km 752 than 10 km2 11541.2 (ha) Lakes with areas greater than 0.5 44 km2 36 km2 9537.5 (ha) Transitional water bodies 19 332 km2 Coastal water bodies 13 2,286 km2 Table 2.1 Water bodies in the Anglian RBD. The major river catchments within the RBD; the Witham, Welland, Nene and Great Ouse, drain catchments of approximately 2010 km2, 1656 km2, 2363 km2, and 8587 km2 respectively. All of these catchments drain into The Wash, between Boston, to the west, and Kings Lynn, to the east (Figure 2.1). Much of this area is fertile low- lying agricultural land, and substantial impact has been made on the rivers by land drainage and intensive farming practices. Eel management plans for Anglian River Basin District Page 3 Figure 2.1 The Anglian RBD. The multitude of smaller catchments within the counties of Norfolk, Suffolk and Essex, typically drain a catchment area of less than 500 km2 each, with the exception of the Colne (534 km2), Chelmer (665 km2) and Stour (1036 km2). The land use varies throughout the counties and includes forestry, industry, and localised pockets of heavy urbanisation, although overall, agriculture dominates. The RBD has a diverse range of river types, from chalk streams such as the Wensum, to slow flowing, highly eutrophic waters such as the lower reaches of the Great Ouse and Stour. The Anglian WFD RBD receives the least rainfall of the 11 RBDs in England and Wales, and is considered the driest of the Environment Agency Regions (Environment Agency, 2006). Prior to the late 1930s, large parts of the RBD were subjected to several hundred years of fenland drainage to create habitable and agricultural land. After the 1940s large areas were drained to optimise the amount of land available for intensive agriculture. This period led to the wide-scale loss of aquatic habitats. However the river systems were still relatively open to migrating eels, except those rivers with Eel management plans for Anglian River Basin District Page 4 mills and locks. In response to the east coast floods in 1953, the emphasis of management changed from drainage to flood defence. This continues to be the leading factor to the present day. This emphasis on flood defence has lead to the closing off of river systems to migratory species with the construction of large-scale tidal defence schemes, tidal flap valves and locks. This has meant that the tidal limit, which used to influence rivers far inland, has been restricted to estuary level. Due to the combination of the semi-arid nature of the Anglian RBD and the high water demands for human use and agriculture, there is a high level of water management and monitoring (requiring in-stream structures, weirs etc). This, combined with historic milling and land drainage means that the majority of rivers within the RBD are highly modified and regulated systems. River engineering structures such as dams, weirs, sluices and locks, barrages and flap valves may act as migration barriers to fish, thus having the potential to seriously affect eel populations in upstream freshwater habitats (Knights and White, 1998). A preliminary assessment has been carried out on the major obstructions to fish migration within the Anglian RBD (Figure 2.2) through a combination of local Fisheries, Flood Defence and Hydrology experience, and field-based evaluation. These barriers have been graded individually in terms of the likelihood of eel passage. Figure 2.2 Distribution of obstructions in the Anglian RBD. Barriers are graded in terms of accessibility for eels. Eel management plans for Anglian River Basin District Page 5 More work is required to assess the potential impact of all barriers within the RBD. In addition to using physical barrier attributes, there should be greater utilisation of existing long-term data sets in assessing possible barrier effect. An example of this approach was used in Essex (A. Piper, pers. comm.), where analysis was undertaken using data from 12 routine electric fishing survey sites upstream and 12 downstream of Bures Mill on the River Stour (Figure 2.3) to assess the potential impact of the mill on the eel populations. This mill is considered the most significant barrier to eel migration on the Stour. Upstream densities of eel were significantly lower than those downstream (P < 0.0005). This analysis was based on minimum density estimates provided by multi-species electric fishing. The use of better quality density data from eel-specific electric fishing will allow a more quantitative assessment of the effect of this and other barriers. Such analyses are planned for the first phase of this and other EMPs, where eel- specific surveys and barriers coincide. 3 (F = 23.53, d.f.=1, p < 0.0005) Below 2.5 Above 2 ) -2 1.5 Density (Ind./100m Density 1 0.5 0 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 Figure 2.3 Mean density of eels >99mm (Ind./100m2) (+/-95% C.I.) above and below Bures Mill, a possible barrier to migration, on the River Stour (n=12) 2.2 Current eel population There is very little commercial catch return information for the Anglian RBD. There has never been a commercial glass eel fishery in operation within the region. The adult eel fishery was relatively strong in the past, although few records were kept. Currently, due to reduced numbers of eels, fishing is patchy and at best a subsistence activity for many of the fishermen. Therefore the present catch return information does not provide the quantity, quality or coverage of information required to adequately assess the population. However reported catch data may be used with limited confidence to highlight trends. The Anglian Region relies almost Eel management plans for Anglian River Basin District Page 6 solely on monitoring data to assess the status of the eel population. The long-term data sets from several rivers have proved invaluable due to the consistent manner in which they have been monitored. 2.2.1 Glass eel recruitment Due to the absence of any commercial glass eel/elver catch data for the region, two monitoring traps have been installed on the lower freshwater/saltwater limit; on the Chelmer and Blackwater Canal at Beeleigh in Essex and on the River Stour at Flatford in Suffolk (Plates 1 & 2). These traps are run annually between April and July and provide an indication of the strength of the glass eel run for that year. Plates 1 & 2 Glass eel/elver trap on the Chelmer and Blackwater canal at Beeleigh in Essex, and on the River Stour at Flatford in Suffolk. The glass eel and elver data for these traps are shown for 2002 to 2006 for Beeleigh (Figure 2.4) and for 2002 to 2005 for Flatford (Figure 2.5). Eel management plans for Anglian River Basin District Page 7 Glass Pigmented 4500 4000 3500 3000 2500 2000 Number 1500 1000 500 0 2002 2003 2004 2005 2006 Figure 2.4 Glass eel catches from Environment Agency monitoring trap, Beeleigh on the River Chelmer, Essex from 2002 – 2006 The trap was not run continuously at Flatford mill in 2006 due to low flows. On the occasions the trap could be run, no glass eels or elvers were caught and none were observed on the weir as in previous years. Glass Pigmented 14000 12000 10000 8000 6000 Number 4000 2000 No data 0 2002 2003 2004 2005 2006 Figure 2.5 Glass eel catches from Environment Agency monitoring trap at Flatford on the River Stour, Suffolk from 2002 – 2005 (trap was not run in 2006).